In the welding industry, the need for improved productivity has led to an increase in demand for high-speed welding with less spattering combined with reliable high quality. Faster welding speeds increase the production quantity per hour, and less spattering reduces the time spent in post-processing for removing spatter attached to workpieces, resulting in improved welding productivity. In particular, if spatter adheres to a component whose appearance is important, the product's value drastically drops. Adhesion of spatter to such components thus needs to be prevented. For this purpose, automatic welding equipment combining the use of a non-consumable electrode that does not generate spatter and a welding material is increasingly being adopted.
Conventional automatic welding equipment achieves high-quality welding without spatter adhesion. However, it is extremely important to secure an appropriate distance among the non-consumable electrode, the welding material (hereinafter also referred to as a “filler wire”), and the welding workpiece (hereinafter referred to as the “workpiece”). In this connection, a method of controlling current running through the welding material is disclosed. (For example, refer to Patent Document 1.)
The conventional automatic welding equipment is described next with reference to FIG. 7, which is a schematic view of conventional automatic welding equipment. As shown in the drawing, the conventional automatic welding equipment includes welding power source 302 that applies welding voltage between tungsten electrode 301, which is a non-consumable electrode, and workpiece 305 to produce welding arc 308; and filler wire power source 303 that supplies power to wire chip 307. Current measuring section 313 is connected between filler wire power source 303 and workpiece 305. Current measuring section 313 is also connected to filler wire current detector 316. Filler wire current detector 316 detects the current running in wire chip 307 via current measuring section 313. Filler wire current detector 316 recognizes the detected current as the current value running in the filler wire, and outputs the value to filler wire vertical movement determination section 310 and threshold current calculator 314.
In the above configuration, an operator lowers filler wire 306 toward a weld pool until it contacts the weld pool. When the operator confirms the contact of filler wire 306 and the weld pool, lowering of filler wire 306 is stopped. A filler wire feeding control procedure is then executed. Welding takes place while comparing the filler wire current value with a reference value. If the filler wire current value changes out of the reference value, the equipment is controlled to stop the supply of current to filler wire 306.
In the conventional automatic welding equipment as configured above, however, no means is provided for detecting a tip position of filler wire 306 in starting welding. Accordingly, the shape of the weld bead in starting welding is variable.
Patent Document 1: Japanese Patent Unexamined Publication No. H9-1334.